By connecting primary and secondary schools in the CARNET network, all content and services on the Internet have become accessible to students and teachers in Croatian schools. Aware of the variety of content accessible to students in this way and of their age, CARNET started implementing a system for filtering inappropriate content at the beginning of 2007. The goal is to make such content inaccessible from school computers.

The CA eTrust Secure Content Manager content filter system is based on the principle of prohibiting the display of websites that belong to certain categories. Every website is categorized according to the content it offers, and the content is filtered by choosing the categories that one does not want to be displayed. The categorization of sites is constantly updated, and new versions of databases are automatically checked every couple of hours. It is also possible to allow or prohibit the display of certain sites manually. Every website can belong to one or several categories.

The categories that CARNET filters for schools are:

Drugs

Gambling

Gambling Related

Gruesome Content

Hate Speech

Hacking

Malicious Sites

Nudity

Profanity

Pornography

School Cheating Information

Spam

Tobacco

Violence

The list of categories is given in English rather than Croatian because of the omnipresence of English on the Internet and the easier categorization of sites that are not from Croatian speaking areas.